Sains Malaysiana 40(11)(2011): 1209–1221 Community Structure and Biomass of Tree Species at Chini Watershed Forest, Pekan, Pahang (Struktur Komuniti dan Biojisim Spesies Pokok di Hutan Lembangan Chini, Pekan, Pahang) M. KHAIRIL*, W.A. WAN JULIANA, M.S. NIZAM & R. FASZLY ABSTRACT A study was conducted to determine the tree species composition, diversity and estimate of above ground biomass at Chini watershed forest. Three types of forest were identified. Thirty plots of 0.1 ha were established in the inland, seasonal flood and riverine forests. A total of 3974 trees with diameter at breast height (dbh) at 5.0 cm and above were recorded. The inland forest recorded 2061 individuals representing 393 species from 164 genera and 57 families; the seasonal flood forest, 1019 individuals representing 268 species from 137 genera and 57 families; and the riverine forest, 894 individuals representing 260 species from 133 genera and 53 families. Endospermum diadenum (Euphorbiaceae), Streblus elongatus (Moraceae) and Aporusa arborea (Euphorbiaceae) was the most important species in the inland forest, seasonal flood forest and the riverine forest, with Importance Value Index (SIVi) of 3.36%, 4.43% and 2.96%, respectively. Euphorbiaceae was the most important family in the inland and riverine forest with FIVi of 14.25% and 12.91% and Myrtaceae in the seasonal flood forest at 12.36%. The Shannon-Weiner diversity index (H’) were considered high in all three forest types at 5.40 (H’max = 5.97) in the inland forest, 5.10 (H’max = 5.54) at the seasonal flood forest and 5.08 (H’max = 5.56) for the riverine forest. Shannon evenness index (J’) in the three types of forest was 0.9. The Sorenson’s community similarity coefficient (CCs) showed that tree species communities between the three forest types had low similarities with CCs= 0.4. The total above ground biomass estimated in the inland forest was 366.2 tan/ha, in the seasonal flood forest was 379.8 tan/ha and in the riverine forest was 401.1 tan/ha. A total of 44 endemic species in Peninsular Malaysia were found and 104 species were listed in the checklist of Conservation Status of Malaysian Trees that utilized the 2009 IUCN Red List Categories by World Conservation Monitoring Centre (WCMC). Keywords: Chini watershed; community similarity; species diversity; tree species biomass; tree species composition ABSTRAK Satu kajian telah dijalankan untuk menentukan komposisi, kepelbagaian dan anggaran biojisim atas tanah spesies pokok di hutan lembangan Chini, Pekan, Pahang. Terdapat tiga jenis hutan telah dikenal pasti di lembangan Chini iaitu hutan pedalaman, banjir bermusim dan riparia. Sebanyak 30 plot yang bersaiz 0.1 ha telah dibina dengan jumlah luas kawasan pensampelan di hutan pedalaman adalah 1.4 ha, hutan banjir bermusim 0.9 ha dan hutan riparian 0.7 ha. Sejumlah 3974 pokok bersaiz 5 cm dbh dan ke atas telah dicatatkan. Hutan pedalaman merekodkan 2061 individu, 393 spesies daripada 164 genus dan 57 famili; hutan banjir bermusim, 1019 individu, 268 spesies daripada 137 genus dan 57 famili; dan hutan riparia, 894 individu, 260 spesies daripada 137 genus dan 53 famili. Endospermum diadenum (Euphorbiaceae), Streblus elongatus (Moraceae) and Aporusa arborea (Euphorbiaceae) merupakan spesies yang mempunyai Nilai Kepentingan (SIVi) spesies tertinggi di hutan pedalaman, hutan banjir bermusim dan hutan riparia dengan masing-masing 3.36%, 4.43% dan 2.96%. Euphorbiaceae merupakan famili terpenting di hutan pedalaman dan hutan riparia dengan Nilai Kepentingan (FIVi) famili masing-masing 14.25% dan 12.91% dan Myrtaceae di hutan banjir bermusim dengan 12.36%. Nilai indeks kepelbagaian Shannon-Weiner (H’) yang dicatatkan didapati tinggi di ketiga-tiga jenis hutan dengan hutan pedalaman 5.40 (H’max= 5.97), hutan banjir bermusim 5.10 (H’max= 5.54) dan hutan riparia 5.07 (H’max= 5.56). Nilai keseragaman Shannon (J’) ketiga-tiga jenis hutan ialah 0.9. Koefisien kesamaan komuniti Sorenson (CCs) menunjukkan komuniti di ketiga-tiga jenis hutan mempunyai nilai kesamaan yang rendah iaitu CCs= 0.4. Jumlah biojisim atas tanah di hutan pedalaman ialah 366.2 tan/ha, di hutan banjir bermusim 379.8 tan/ha dan di hutan riparia 401.1 tan/ha. Sejumlah 44 spesies endemik di Semenanjung Malaysia telah dikenalpasti hadir dalam kajian ini dan sebanyak 104 spesies pokok telah disenaraikan dalam senarai pemuliharaan IUCN Red list Categories 2009 oleh World Conservation Monitoring Centre (WCMC). Kata kunci: Kepelbagaian spesies; kesamaan komuniti; komposisi spesies pokok; lembangan Chini 1210 INTRODUCTION the eco-tourism sites in Pahang (Rancangan Tempatan Daerah Pekan 2002-2015). However, activities such as Wetlands include both land ecosystem whose ecological timber harvesting, oil palm plantation, infrastructure function is strongly influenced by water, and aquatic development and mining in Chini watershed forests had ecosystem with special characteristics due to its shallowness disturbed the ecosystem balance (Mushrifah et al. 2005). and the proximity to land (Lugo et al. 1990; Roggeri 1995). These activities also cause habitat loss of flora and fauna Their often rich variety of resources makes them highly and gave negative impacts on the indigenous people, who valuable to the peoples who live or regularly stay in them. tend to hunt wildlife, find rattans and other plants as daily During the last few decades tropical wetlands have been livelihood and also as traditional medicine (Mustaffa destroyed or considerably altered. Dams and embankments 2005). now prevent water from spreading into the floodplains The degradation of both aquatic and terrestrial of several rivers, like the Senegal, Volta and Nile. In components of the Chini ecosystem has led to many Southeast Asia, the wetland areas in many countries have studies. Most studies at Chini concentrated on the aquatic been destroyed by activities such as agriculture, logging component (e.g. Khatijah 2005; Mushrifah et al. 2005, and development (Roggeri 1995; Williams 1990). 2009; Suhaimi et al. 2009). There are very few studies on Malaysia is one of the countries that have wetland the terrestrial component especially on the forest structure areas and it was estimated about 3.3 million ha that is of the watershed forests that surround the lake. There are equal to only 10% of the total area of the country (Wetlands several studies on tree species composition and diversity at International 2009). The important freshwater habitats in Chini Forest Reserve. Siti Najmi (2005) conducted a study the country are the highland forests and wetlands (both at an inland forest of Sg. Jemberau, Norwahidah (2005) forested wetlands and water bodies such as rivers, lakes conducted a comparative study between riparian and inland and lagoon). Forests in the highlands, often referred to as forest of Sg. Chini, Fajariah (2004) at inland forests of natural ‘water towers’ because of their water catchment Bukit Tebakang and Norsiah (2005) at riparian forests of function help provide us with continuous clean supply of Sg. Chini. All those studies covered a small local scale and water. They are the source for most of the country’s water limited area only. Thus, this study was conducted to cover resources (Wetlands International 2009). Wetlands provide a larger landscape scale of vegetation characterization at a range of natural ecological and hydrological functions the Chini watershed forests, Pekan, Pahang. therefore they have important roles in water supply, water The objectives of this study were to determine the purification and flood control (Roggeri 1995; Walter trees species composition, diversity and above ground 2002). biomass in Chini watershed forest. As an area that has Both the highland forests and wetlands also contribute been declared as a Man and Biosphere Reserve site by many socio-economic benefits in terms of the goods and UNESCO, Tasik Chini needs a lot of baseline data that can services (such as forestry and fisheries resources). They be used to conserve this area. Therefore, the endemism also serves as critical biodiversity conservation needs and conservation status of tree species were also included such as by providing refuge for many species of plants in the study. Besides that, Tasik Chini is one of the areas and animals (Lugo et al.1990; Roggeri 1995; Williams that will be developed under the East Corridor Economic 1990). One of the efforts by the Malaysian government Region (ECER) project as Chini State Park. Thus, the data and international societies in order to conserve the wetland and information on tree species community structure and areas was by the declaration of Tasik Bera in Pahang, diversity from this study is very important and will be Sungai Pulai, Tanjung Piai and Pulau Kukup in Johor and used as a guideline for a sound management plan and Kuching Wetland National Park as Ramsar Sites (Wetlands conservation activities at Chini. International 2009). Pahang is the largest state in Peninsular Malaysia and METHODOLOGY the forest covered 3,596,585 ha that is equal to 42.7% of the total area of Pahang (Jabatan Perhutanan Semenanjung The Tasik Chini basin includes a lush tropical regenerating Malaysia 2008). There were two natural lakes in Pahang logged-over forest covering an area of 4975 ha from namely, Tasik Bera and Tasik Chini. Tasik Chini is the which, many rivers and streams feed the lake (Figure 1.). second largest natural freshwater lake in Peninsular The area of the lake is not constant and the area can be Malaysia after Tasik Bera. The Chini watershed includes between 150 and 350 ha due to flooding especially during several small rivers and stream, a lake, swamps and the raining season between October to November (Chong lowland forests. For over 30 years, people have visited the 2001). Based on the information given by the villagers, Tasik Chini for fishing, kayaking, camping, jungle tracking during the flooding season, the water level of the lake can and visited the Orang Asli settlements (Mohd Ekhwan et al.